Guri- Si is a medium sized city about 40 minutes outside of Seoul. The best thing about Guri is its location. You can hop on one of numerous buses and they take you about 15-20 mins to the main subways lines. It also has a mountain called Achasan. Aside from that it is similar to most cities in Korea. There are a large amount of foreigners here as there are many many hagwons in Guri. Some meet up often at a bar called 'Moonblues' but there are many scattered around the city in the different areas. All in all I cant really complain too much about Guri, its been a good place to us and I think for first timers to korea its perfect as you have every convenience you may need readily available.
Theres a bit more info over at wiki. The picture on the site if from jajang lake park which is a pretty place in Guri to chill out at.
http://en.wikipedia.org/wiki/Guri
Jajang Park
Guri-Si
View from Achasan Mountain